Dietary antioxidant intake and the risk of cardia cancer and noncardia cancer of the intestinal and diffuse types: a population-based case-control study in Sweden.

In spite of diverging incidence trends, subsite, and subtype-specific gastric cancer data on the association with dietary antioxidants are sparse. We aimed to test whether the apparent protective effect of antioxidants is mainly confined to noncardia (distal) cancer of the intestinal subtype, to which most of the incidence decline in gastric cancer has been ascribed. In a Swedish study base (total population 1.3 million), we interviewed 567 cases uniformly classified to subsite (cardia vs. noncardia) and subtype (intestinal vs. diffuse), and 1165 population-based controls, frequency matched for age and sex. Serologic data on H. pylori status was available for a subset of 542 individuals. Ascorbic acid (vitamin C) was inversely associated with all subsites and subtypes of gastric cancer in a significant dose-response manner (all p<0.05), with risk reductions between 40% and 60%. beta-carotene was also strongly and negatively associated with risk, particularly with the intestinal type. The associations with alpha-tocopherol (vitamin E) were less clear. The highest parallel intake of all three antioxidants (quartiles 4), compared to those with the lowest parallel intakes (quartiles 1), was associated with a 70% lower risk of developing noncardia cancer (OR 0.3, 95% CI 0.1-0.9). Our results suggest that antioxidants might be especially beneficial among subjects at increased risk for gastric cancer such as smokers and those infected by H. pylori. We conclude that a high intake of antioxidants, as a consequence of high consumption of fruit and vegetables, may lower the risk not only for gastric cancer of the intestinal type, but also for diffuse type adenocarcinoma and cardia cancer.